Burner Manufacturing 240-106027729 Standard · Burner manufacturing and the effective management...

PCM Reference : 240-53459108

SCOT Study Committee Number/Name : Boiler Study Committee

Title: Burner Manufacturing Standard

Unique Identifier: 240-106027729

Alternative Reference Number: N/A

Area of Applicability: All fossil power plants within Eskom

Documentation Type: Standard

Revision: 1

Total Pages: 26

Next Review Date: December 2021

Disclosure Classification: CONTROLLED DISCLOSURE

Compiled by Approved by Authorised by

………………………………….. ………………………………….. …………………………………..

Dr. Robert Clark

Chief Engineer

Anton Hart

Boiler Auxiliary Manager

Yokesh Singh

Boiler Study Committee

Date: …………………………… Date: …………………………… Date: ……………………………

Supported by SCOT TC

…………………………………..

Prof. Saneshan Govender

Chairman Power Plant TC

Date: ……………………………

Standard

Technology

Burner Manufacturing Standard

CONTROLLED DISCLOSURE

When downloaded from the EDMS, this document is uncontrolled and the responsibility rests with the user to ensure it is in line with the authorised version on the system.


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CONTENTS

Page

EXECUTIVE SUMMARY .............................................................................................................................................. 4

1. INTRODUCTION ...................................................................................................................................................... 5

2. SUPPORTING CLAUSES ........................................................................................................................................ 5

2.1 SCOPE .............................................................................................................................................................. 5 2.1.1 Purpose ..................................................................................................................................................... 5 2.1.2 Applicability................................................................................................................................................ 5

2.2 NORMATIVE / INFORMATIVE REFERENCES ................................................................................................ 6 2.2.1 Normative .................................................................................................................................................. 6 2.2.2 Informative ................................................................................................................................................. 6

2.3 DEFINITIONS .................................................................................................................................................... 7 2.3.1 Disclosure Classification ........................................................................................................................... 7

2.4 ABBREVIATIONS .............................................................................................................................................. 7 2.5 ROLES AND RESPONSIBILITIES .................................................................................................................... 8 2.6 PROCESS FOR MONITORING ........................................................................................................................ 8 2.7 RELATED / SUPPORTING DOCUMENTS ....................................................................................................... 8

3. STANDARD FOR BURNER MANUFACTURING AND REFURBISHMENT .......................................................... 8

3.1 TOLERANCES .................................................................................................................................................. 8 3.1.1 Flatness and straightness ......................................................................................................................... 9 3.1.2 Circularity ................................................................................................................................................... 9 3.1.3 Cylindricity. ................................................................................................................................................ 9 3.1.4 Parallelism. ................................................................................................................................................ 9 3.1.5 Perpendicularity. ........................................................................................................................................ 9 3.1.6 Symmetry ................................................................................................................................................ 10 3.1.7 Coaxiality ................................................................................................................................................. 10 3.1.8 Circular run-out ........................................................................................................................................ 10

3.2 FORMING ........................................................................................................................................................ 11 3.2.1 Hot and cold bending of profiles .............................................................................................................. 11 3.2.2 Edging and pressing ................................................................................................................................ 12 3.2.3 Rolling ...................................................................................................................................................... 12

3.3 WELDED CONSTRUCTION ........................................................................................................................... 13 3.3.1 Allowable deviation on length dimensions ............................................................................................... 13 3.3.2 Allowable deviations on angular dimensions .......................................................................................... 13 3.3.3 Allowable deviation on straightness, flatness, and parallelism ............................................................... 15 3.3.4 Surface Alignment ................................................................................................................................... 15

3.4 MACHINING .................................................................................................................................................... 16 3.4.1 Dimensions for length and angles ........................................................................................................... 16 This Standard applies to: .................................................................................................................................. 16 3.4.2 Allowable tolerances on linear dimensions ............................................................................................. 16 3.4.3 Allowable tolerances on broken edges (for rounding radii and chamfer heights) ................................... 16 3.4.4 Allowable tolerances on angular dimensions .......................................................................................... 17

3.5 WELDING ........................................................................................................................................................ 17 3.5.1 Welding procedure specifications and Welding Procedure Qualification Records ................................. 17 3.5.2 Welder approval ...................................................................................................................................... 17 3.5.3 Repairs .................................................................................................................................................... 17 3.5.4 Weld gap ................................................................................................................................................. 18 3.5.5 Hard-facing .............................................................................................................................................. 18 3.5.6 Separation of materials ........................................................................................................................... 19 3.5.7 Surface finishes ....................................................................................................................................... 19 3.5.8 Non-destructive testing ............................................................................................................................ 19

3.6 QUALITY CONTROL ....................................................................................................................................... 20 3.6.1 Inspection and test plans ......................................................................................................................... 20





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3.6.2 Fit for purpose ......................................................................................................................................... 20 3.6.3 Material certification ................................................................................................................................ 20 3.6.4 Material handling ..................................................................................................................................... 20 3.6.5 Storage .................................................................................................................................................... 20 3.6.6 Documentation packages ........................................................................................................................ 21

3.7 DRAWINGS ..................................................................................................................................................... 21 3.7.1 Manufacturing drawings .......................................................................................................................... 22 3.7.2 Tolerances on drawings .......................................................................................................................... 22 3.7.3 Critical dimensions .................................................................................................................................. 22

3.8 SUPPLIER ASSESSMENTS ........................................................................................................................... 22 3.9 GENERAL ASSEMBLY ................................................................................................................................... 22

3.9.1 Bolting ...................................................................................................................................................... 22 3.9.2 Passivation and pickling .......................................................................................................................... 22 3.9.3 Painting .................................................................................................................................................... 23 3.9.4 Jigs .......................................................................................................................................................... 23 3.9.5 Transportation frames ............................................................................................................................. 23

3.10 MATERIAL CERTIFICATION ........................................................................................................................ 23 3.10.1 Material of construction ......................................................................................................................... 23 3.10.2 Certificates of compliance ..................................................................................................................... 23 3.10.3 Material identification ............................................................................................................................. 24 3.10.4 Inspection and test plans ....................................................................................................................... 24

4. AUTHORISATION .................................................................................................................................................. 25

5. REVISIONS ............................................................................................................................................................ 25

6. DEVELOPMENT TEAM ......................................................................................................................................... 25

7. ACKNOWLEDGEMENTS ...................................................................................................................................... 26

FIGURES

Figure 1: Forms A to C ............................................................................................................................................... 12 Figure 2: Examples (Fig 1-5) on how to specify Dimensions on Drawings ................................................................ 14

TABLES

Table 1: Tolerances for Flatness and Straightness ...................................................................................................... 9 Table 2: Symmetry Tolerances ..................................................................................................................................... 9 Table 3: Perpedicularity Tolerances ........................................................................................................................... 10 Table 4: General Tolerances on Symmetry ................................................................................................................ 10 Table 5: Circular Run-out Tolerances ......................................................................................................................... 11 Table 6: Allowable Deviation after Forming ................................................................................................................ 11 Table 7: Length Tolerances on Cutting ...................................................................................................................... 11 Table 8: Tolerances for Edged or Pressed Components ........................................................................................... 12 Table 9: Allowable Deviation after Rolling in mm ....................................................................................................... 12 Table 10: Allowable Deviation on Length Dimensions for Welded Products ............................................................. 13 Table 11: Deviations on Angular Dimensions ............................................................................................................ 15 Table 12: Deviation on Angular Dimension Continued ............................................................................................... 15 Table 13: Straightness, Flatness and Parallelism Tolerances ................................................................................... 15 Table 14: Allowable Tolerances on Linear Dimensions ............................................................................................. 16 Table 15: Allowable Tolerances on cutting (Sawing) ................................................................................................. 16 Table 16: Allowable Tolerance on Broken Edges ...................................................................................................... 16 Table 17: Allowable Tolerances on Angular Dimensions ........................................................................................... 17 Table 18: Cracking of hard-facing .............................................................................................................................. 18 Table 19: Single and Cluster Porosity ........................................................................................................................ 18 Table 20: Linear Porosity ............................................................................................................................................ 19





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EXECUTIVE SUMMARY

Eskom has embarked on an ambitious plan to design, manufacture and install Low NOx Burners within

the fleet of power stations to ensure that Eskom is compliant with the environmental regulations for

nitrous oxide emissions.

The design of the burners is based on empirical standards, rather than accepted engineering design

codes. The fabrication of the burners is not based on a manufacturing code. The manufacturing process

is based on an array of codes that is put in place prior to the award of the contract. The purpose of this

Standard is to specify what codes and standards will be acceptable by Eskom during the manufacture of

the Low NOx burners for Eskom’s fleet of power stations.

The successful implementation of this Standard will ensure that all Low NOx burners within Eskom’s

power plants are constructed to best international practices. Any compromise in the manufacturing

process of a Low NOx burner could be potentially dangerous to plant and personnel, and could

negatively impact on the functionality of the burner.

The Standard shall furthermore be applied to any burner refurbishment work carried out at power

stations where Low NOx burner components are to be fitted.





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1. INTRODUCTION

Burner manufacturing and the effective management thereof is always an area of concern within the

power generation fraternity. Pulverised fuel burners contain high energy combustible medium that could

be potentially dangerous in the event of a failure. It is therefore of paramount importance that the

pulverised fuel burners are effectively fabricated and maintained to Eskom’s acceptance standards.

This Standard specifies the minimum acceptable specifications required to manufacture Low NOx

burners for Eskom. Compliance to this Standard is of paramount importance, as the velocities within a

Low NOx burner are critical to the effective operation of the burner.

2. SUPPORTING CLAUSES

2.1 SCOPE

The scope of this Standard is limited to the pulverised fuel burners on the fossil fuel power plants. It is

specifically aimed at the manufacture of the Low NOx burners, and the refurbishment of existing PF

burners where Low NOx burner components are to be fitted. The Standard can be applied as a guideline

to all PF burner refurbishment work within Eskom.

2.1.1 Purpose

This document sets out the minimum standards for burner manufacturing and refurbishment work at

Eskom’s power plants. The document furthermore includes packaging, storage and documentation

requirements applicable to burner components.

2.1.2 Applicability

This Standard is limited to the pulverised fuel burners on the fossil fuel power plants. It is specifically

aimed at the manufacture of the Low NOx burners, and the refurbishment of existing PF burners where

Low NOx burner components are to be fitted. The boundary limits are from the windbox flange to the

burner tip, including the core air systems.

Where modifications as per the Eskom Change Management process are made to existing PF burners,

either this Standard will be applied or the code to which the original burners were designed and

manufactured. This Standard does not supersede any code requirements.

This standard excludes:

The fuel oil lance,

Instrument tapping lines,

The positioning and welding of thermocouples.

This document shall apply throughout Eskom Holdings Limited Divisions where PF burners are used.





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2.2 NORMATIVE / INFORMATIVE REFERENCES

Parties using this document shall apply the most recent edition of the documents listed in the following

paragraphs.

2.2.1 Normative

[1] ISO 9001 Quality Management Systems.

[2] BS EN 1011-3. Welding – Requirements for welding of metallic materials.

[3] BS EN ISO 3834. Quality requirements for fusion welding of metallic materials. Parts 1 to 6.

[4] BS EN ISO 5817. Fusion-welding joints in steel, nickel and titanium and their alloys - Quality levels for imperfections.

[5] BS EN 10204 - Metallic products – Types of inspection documents.

[6] BS EN ISO 15609. Specification and qualification of welding procedures for metallic materials –

Welding procedure specification.

[7] BS EN ISO 15614-1. Specification and qualification of welding procedures for metallic materials –

Welding procedure test. Arc and gas welding of steels and arc welding of nickel and nickel alloys.

[8] BS EN ISO 15614-7. Specification and qualification of welding procedures for metallic materials –

Welding procedure test. Overlay welding.

[9] 240-83539994 - Eskom NDT Personnel Approval (NPA) for Quality Related Special Processes on

Eskom Plant Standard.

[10] 240-83540088 - Requirements for Non-Destructive Testing (NDT) on Eskom Plant Standard.

[11] The Occupational Health and Safety Act and Regulations (Act No 85 of 1993).

[12] DIN 406-10 – Engineering drawing practice; dimensioning; concepts and general principles.

[13] DIN 406-11 - Engineering drawing practice; dimensioning; principles of application.

[14] DIN 406-11 Annex 1 - Engineering drawing practice; dimensioning - part 11: concepts and general

principles; processing of raw components.

[15] DIN 406-12 - Engineering drawing practice; dimensioning; tolerances on linear and angular

dimensions (modified version of ISO 406:1987).

[16] DIN ISO 2768-1 – General tolerances on linear and angular dimensions without individual

tolerance indications.

[17] DIN ISO 2768-2 – General tolerances on features without individual tolerance indications.

[18] DIN EN ISO 1101 – Geometrical product specification (GPS) - Geometrical tolerancing –

Tolerances on form, direction, location and run-out.

[19] DIN EN ISO 13920 - Welding – General tolerances on welded constructions – Dimensions for

length, angles, shapes and position.

[20] 240-86973501 Revision 1 – Engineering Drawing Standard – Common requirements.

[21] 240-106628253 – Standards for Welding Requirements on Eskom Plant.

2.2.2 Informative

[22] 240-71432150 - KKS Plant Labelling and Equipment Description Standard.

[23] Steinmuller Engineering SE 001-10. General tolerances. October 2014.





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2.3 DEFINITIONS

Definition Description

Appointed Inspection

Authority

An Inspection Authority as specified by the OHS Act.

Circularity The roundness specification of an object.

Coaxiality Two or more dimensions that share a common axis.

Cylindrical Related to or having the form of a cylinder.

Deviation A variance from the accepted norm.

Flatness Defines how much a surface on a part may vary from the ideal flat

plane. The distance between the parallel planes is the stated flatness

control tolerance value.

Modification A permanent or temporary change to the design base. Any

modification shall be managed within the Eskom ECM process.

Ovality A measure of the deviation from circularity.

Parallelism The degree to which a features orientation may vary with respect to

the reference datum.

Pickle & passivate Pickle and passivate are chemical treatments applied to the surface of

stainless steel to remove contaminants and assist the formation of a

continuous chromium-oxide passive film.

Perpendicularity Relationship of two lines which meet at a right angle.

Repair The restoration to original standards by the application of heat or

welding.

Roundness Is the measure of how closely the shape of an object approaches that

of a circle.

Symmetry When an object is invariant to a transformation.

Tolerance Permissible limits of variation in an object.

2.3.1 Disclosure Classification

Controlled disclosure: controlled disclosure to external parties (either enforced by law, or

discretionary).

2.4 ABBREVIATIONS

Abbreviation Description

CoE Centre of Excellence

EDWL Engineering Design Work Lead

IWE International Welding Engineer

IWT International Welding Technologist





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Abbreviation Description

LDE Lead Discipline Engineer

NDT Non-destructive testing

OD Outside Diameter

OHS Occupational Health and Safety

PQR Procedure qualification record

WPQR Welding procedure qualification record

WPS Welding procedure specification

2.5 ROLES AND RESPONSIBILITIES

It is the responsibility of the Engineering Design Work Lead to ensure that this Standard is specified

when Manufacturing Contractors tender on the manufacture or refurbishment of burner’s or components

within Eskom.

It is the responsibility of the Eskom Contract Manager to ensure that this Standard is complied with in full

when the Manufacturing Contractor manufactures or refurbishes burners or Low NOx burner

components for Eskom. The Contract Manager may under no circumstances deviate from this Standard.

In the absence of an EDWL, any deviation from this Standard will be approved by the appropriate CoE

Manager.

2.6 PROCESS FOR MONITORING

The EDWL shall ensure that this Standard is adhered to in full during the manufacture of the Low NOx

burners on Eskom’s power plants.

2.7 RELATED / SUPPORTING DOCUMENTS

The document does not supersede any previous Burner Manufacturing Standard within Eskom.

3. STANDARD FOR BURNER MANUFACTURING AND REFURBISHMENT

Eskom has taken a stringent approach with respect to the acceptable tolerances for Low NOx burners.

The requirement for tight tolerances is in place to ensure that components will perform to the desired

design requirements. Tight tolerances also eliminate secondary operations like machining, which

reduces costs. The tolerances are extracted from various engineering manufacturing codes. With the

correct manufacturing equipment and effort, these tolerances are achievable on a consistent basis.

It is the Manufactures responsibility to allow for the variable shrink in the material due to the

manufacturing process. The summation of part component shrinkage shall not be used as justification for

not achieving the overall critical dimensions on a burner or component.

3.1 TOLERANCES

General tolerances within the scope of this standard are applicable to nominal dimensions as indicated

on the manufacturing drawings. Where the tolerances are not explicitly stated on the drawing, the

general tolerances as stated in this Standard shall apply.





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Any deviation to the general tolerances must be specified on the drawing and accepted by Eskom’s

EDWL before work may commence.

3.1.1 Flatness and straightness

The general tolerance for flatness and straightness is shown in Table 1. For straightness tolerances the

length of the surface is applicable and for flatness tolerances the larger side length of the surface or the

diameter of the circular area is applicable.

Table 1: Tolerances for Flatness and Straightness

Degree of

accuracy

General tolerances in mm on straightness and flatness on nominal dimensions

Up to 10 Over 10 to 30 Over 30 to 100 Over 100 to 300

Over 300 to 1000

Over 1000 to 3000

H 0.02 0.05 0.1 0.2 0.3 0.4

K 0.05 0.1 0.2 0.4 0.6 0.8

L 0.1 0.2 0.4 0.8 1.2 1.2

3.1.2 Circularity

The general tolerance for circularity (roundness) is equal to the numerical of the diameter tolerance, but

should never be greater than the value specified for concentricity.

Table 2: Symmetry Tolerances

Degree of accuracy Symmetry tolerances for nominal dimensions in mm


H 0.5

K 0.6 0.8 1.0

L 0.8 1 1.5 2.0

3.1.3 Cylindricity.

General tolerances for cylindricity are not specified (see notes in DIN ISO 2768-2.)

3.1.4 Parallelism.

The general tolerance for parallelism is equal to the numerical value of the size tolerance or the flatness /

straightness tolerance, whichever is greater. The longer of the two features will be taken as the datum; if

the features are of equal nominal length, either may be taken as the datum.

3.1.5 Perpendicularity.

The general tolerances for perpendicularity are shown in Table 3. The longer of the two sides forming

the right angle shall be taken as the datum; if the sides are of equal length, either side may be taken as

the datum.





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Table 3: Perpedicularity Tolerances

Degree of accuracy

Perpendicularity tolerances on ranges of lengths of the shorter side in mm

up to 100 over 100 to 300

over 300 to 1.000

over 1.000 to 3.000

H 0,2 0,3 0,4 0,5

K 0,4 0,6 0,8 1

L 0,6 1,0 1,5 2

3.1.6 Symmetry

The general tolerances on symmetry are shown in Table 4. The longer of the two features shall be taken

as the datum.

Table 4: General Tolerances on Symmetry

Degree of accuracy Symmetry tolerances for nominal dimensions in mm


H 0.5

K 0.6 0.8 1.0

L 0.8 1 1.5 2.0

3.1.7 Coaxiality

General tolerances on coaxiality are not specified in this Standard. It should be noted however that in

extreme circumstances, the deviation in coaxiality may be as great as the tolerance on circular radial

run-out as stated in this Standard. The deviation in radial run-out comprises the deviation in coaxiality

and the deviation in circularity.

3.1.8 Circular run-out

The general tolerances on circular run-out (radial, axial and any surface of revolution) are as stated in

Table 5. For general tolerances on circular run-out, the bearing surfaces shall be taken as the datum, if

they are designated as such. For circular radial run-out, the larger of the two features shall be taken as

the datum; if the features are of equal length, either may be taken as the datum. The tolerance class for

symmetry and circular run-out is “L”, which does not need to be specified on the drawing. More accurate

individual measurements must be specified on the drawing, if required.





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Table 5: Circular Run-out Tolerances

3.2 FORMING

This section specifies the allowable deviations on nominal dimensions for formed components. In general

the degree of accuracy for forming is given in the Tables 6 and 7 below. These tolerances need not be specified

on the drawings. If a higher accuracy is required for individual dimensions, this should be agreed upon with the

Manufacturer and specified on the drawings.

3.2.1 Hot and cold bending of profiles

Table 6: Allowable Deviation after Forming

Allowable deviation on nominal dimension in mm

up to 6

over 6 to 30

Over 30 to

120

Over 120 to

400

over 400 to

1.000

over 1.000

to 2.000

over 2.000

to 4.000

over 4.000

to 8.000

over 8.000

to 12.000

over 12.000

to 16.000

over 16.000

to 20.000

± 0.5 ± 1 ± 1,5 ± 2 ± 3 ± 4 ± 6 ± 8 ± 10 ± 12 ± 12

Table 7: Length Tolerances on Cutting

Subject

Cut-off length (nominal dimension), measurement in mm

up to 400 over 400 to 1.000 over 1.000 to 4.000 over 4.000 to

12.000 over 12.000

Profiles and bars, plates

± 2 ± 3 ± 4 ± 5 ± 6

Tolerance class Circular run-out tolerances in mm

H 0,1

K 0,2

L 0,5





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3.2.2 Edging and pressing

Forms A to C and Table 8 specify the permissible tolerances for an edged or pressed component.

Form A Form B Form C

Figure 1: Forms A to C

Table 8: Tolerances for Edged or Pressed Components

Method

Allowable deviation in b and h

Length < 2.000 Length 2.000 to 4.000

Wall thickness t

Form b h b h

Edging

≤ 5 A ± 2 - ± 3 -

B, C ± 2 ± 3 ± 3 ± 4

5 to 10 A ± 4 - ± 5 -

B, C ± 4 ± 6 ± 5 ± 8

10 to 18 A ± 6 - ± 8 -

B, C ± 6 ± 8 ± 8 ± 10

Pressing 18 to 30 A ± 6 - ± 8 -

B, C ± 6 ± 8 ± 8 ± 10

3.2.3 Rolling

Table 9: Allowable Deviation after Rolling in mm

Diameter Allowable deviation Deviation from developed length through rolling, weld

seam truncation or exaggeration

Out of roundness Circumference

0,005 x Length

Up to 600 1% +5

-3 over 600

to 1.000

1% max. 8

over 1.000 max. 10 +8

-5

All cylinders and cones shall be re-rolled after welding to ensure that the degree of circularity is within

the prescribed tolerances as stated in this Standard. It is the Manufacturers responsibility to ensure that

the tolerances are achieved after rolling.

Inch bending is not permissible on cones and cylinders.





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3.3 WELDED CONSTRUCTION

The allowable deviations of this Standard are applicable to dimensions without tolerance limits on nominal

dimensions of welded components. They are applicable to welded constructions if the drawings, delivery

requirements or other documentation are referenced to this Standard.

The deviations are applicable to length (linear) dimensions on welded components and welded constructions

such as outside and inside dimensions, widths and angular dimensions.

3.3.1 Allowable deviation on length dimensions

Table 10: Allowable Deviation on Length Dimensions for Welded Products

3.3.2 Allowable deviations on angular dimensions

For the allowable deviations on angular dimensions, the shorter leg serves as the datum. Its length may

also be given from a specific reference point and only in this instance is the reference point to be

specified on the drawing. For allowable deviations, refer to Tables 11 and 12. If no angular dimensions

are shown on the drawings but rather linear dimensions, then the allowable deviations are applicable in

mm/m. Examples of how to specify dimensions on drawings (angle and length) are shown in Figure 2.

The degree of accuracy for nominal dimensions is B. These tolerances need not be specifically indicated

on the manufacturing drawings. The required tolerances must be specified on the drawings should it be

required that a specific dimension must be more accurate.

Allowable deviation on nominal dimensions in mm

Degree of accuracy

2 to 30

over 30 to 120

over 120 to 315

over 315 to 1.000

over 1.000

to 2.000

over 2.000 to

4.000

over 4.000 to

8.000

over 8.000

to 12.000

over 12.000

to 16.000

over 16.000

to 20.000

over 20.000

A

±1

±1 ±1 ±2 ± 3 ±4 ± 5 ± 6 ± 7 ± 8 ± 9

B ±2 ±2 ±3 ± 4 ± 6 ± 8 ±10 ±12 ±14 ±16

C ±3 ±4 ±6 ± 8 ±11 ±14 ±18 ±21 ±24 ±27

D ±4 ±7 ±9 ±12 ±16 ±21 ±27 ±32 ±36 ±40





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Figure 2: Examples (Fig 1-5) on how to specify Dimensions on Drawings





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Table 11: Deviations on Angular Dimensions

Degree of accuracy

Nominal dimension (mm) Length or shorter leg

Up to 315 over 315 to 1000

over 1000

Allowable angular deviation ∆ α in ' or °

A ± 20' ± 15' ±10'

B ± 45' ± 30' ± 20'

C ± 1° ± 45' ± 30'

D ± 1°30' ± 1°15' ± 1°

Table 12: Deviation on Angular Dimension Continued

Degree of accuracy

Nominal dimension (mm) Length or shorter leg

Up to 315 over 315 to 1000

over 1000

Calculated and rounded allowable tolerances in mm/m

A ± 6 ± 4,5 ± 3

B ± 13 ± 9 ± 6

C ± 18 ± 13 ± 9

D ± 26 ± 22 ± 18

3.3.3 Allowable deviation on straightness, flatness, and parallelism

The straightness, flatness, and parallelism tolerances shown in Table 13 are applicable for overall

dimensions of a welded component or welded construction as well as for part lengths.

Table 13: Straightness, Flatness and Parallelism Tolerances

The degree of accuracy measurement for shape and orientation is F. These tolerances need not be specifically

indicated on the manufacturing drawings. The required tolerances must be specified on the drawings should it

be required that a specific dimension must be more accurate.

3.3.4 Surface Alignment

The surface alignment of adjacent plates shall not exceed the values as stated in BS EN 5817 class B,

which states that the surface tolerance may be:

- 0.1 times the plate thickness

- A maximum deviation of 3 mm is allowed for platework thicker than 30 mm.

Straightness, flatness and parallelism tolerances

Tolerance class

over 30 to

120

over 120 to 315

over 315 to

1.000

over 1000

to 2.000

over 2000 to

4.000

over 4.000

to 8.000

over 8.000

to 12.000

over 12.000

to 16.000

over 16.000

to 20.000

over 20.000

E 0,5 1 1,5 2 3 4 5 6 7 8

F 1 1,5 3 4,5 6 8 10 12 14 16

G 1,5 3 5,5 9 11 16 20 22 25 25

H 2.5 5 9 14 18 26 32 36 40 40





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3.4 MACHINING

3.4.1 Dimensions for length and angles

General tolerances within this specification are applied to machined parts for all types of materials unless

other standards are specified for special manufacturing processes.

This Standard applies to:

i. Linear dimensions. That is the external size, internal size, step size, diameter, radii and others.

ii. Fillet radii and chamfer heights.

iii. Angular dimensions (including specified or unspecified angular dimensions e.g. 90° or angles of

uniform polygons).

iv. Linear and angular dimensions of joined parts.

3.4.2 Allowable tolerances on linear dimensions

Table 14: Allowable Tolerances on Linear Dimensions

Tolerance Class Tolerances on nominal dimensions (mm)

Abbreviation Category 0,5 to 3

over 3 to 6

over 6

to 30

over 30 to

120

over 120

to 400

over 400

to 1000

Over 1000

to 2000

over 2000

to 4000

f fine 0,05 0,05 0,1 0,15 0,2 0,3 0,5 0,8

m medium 0,1 0,1 0,2 0,3 0,5 0,8 1,2 2

c coarse 0,2 0,3 0,5 0,8 1,2 2 3 4

v Very coarse - 0,5 1 1,5 2,5 4 6 6

Table 15: Allowable Tolerances on cutting (Sawing)

Profile up to 400 over 400 to 1.000

over 1.000 to 4.000

over 4.000 to 12.000

over 12.000

Profiled and formed sections by profile height

Up to120 ± 1 ± 2 ± 3 ± 4 ± 5

over 120 to 400

± 1,5 ± 3 ± 4 ± 5 ± 6

over 400 ± 3 ± 4 ± 5 ± 6 ± 7

Pipes

Ø up to 114,3 ± 2 ± 3 ± 4

Ø over 114,3 to 457

± 4 ± 5

Ø over 457 ± 5 ± 6

3.4.3 Allowable tolerances on broken edges (for rounding radii and chamfer heights)

Table 16: Allowable Tolerance on Broken Edges

Tolerance class Allowable tolerances on nominal dimensions (mm)

Abbreviation Category from 0,5 to 3

over 3 to 6

over 6

f fine ± 0,2 ± 0,5 ± 1

m medium

c coarse ± 0,4 ± 1 ± 2

v very coarse





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3.4.4 Allowable tolerances on angular dimensions

Table 17: Allowable Tolerances on Angular Dimensions

Tolerance class Allowable tolerances on length ranges in mm, for the shorter length of the relevant angle

Abbreviation Category up to 10

over 10 to 50

over 50 to 120

over 120 to 400

over 400

f fine ± 1° ± 0° 30' ± 0° 20' ± 0° 10' ± 0° 5'

m medium

c coarse ± 1°30' ± 1° ± 0° 30' ± 0° 15' ± 0° 10'

v very coarse ± 3° ± 2° ± 1° ± 0° 30' ± 0° 20'

For general work the acceptance standard is very coarse, for which no specific note is required on the

drawing. Dimensions requiring specific tolerances must be recorded on the drawing.

3.5 WELDING

It is essential that all welding related activities during manufacture, fabrication and repair conform to

Eskom’s latest welding requirements. For this application, the Standard for Welding Requirements on

Eskom Plant (240-106628253) shall be implemented.

3.5.1 Welding procedure specifications and Welding Procedure Qualification Records

All welding procedure specifications and welding procedure qualification records applicable to this

contract shall be handed over to Eskom’s IWE for approval prior to the commencement of work. Work

may not commence until all WPS’s and WPQR’s have been accepted by Eskom.

All WPQR’s and WPS’s presented to Eskom for acceptance shall conform to the latest requirements of

the applicable EN Standards and the Eskom Standard for Welding Requirements on Eskom Plant.

Contractor shall state in the tender returnable documentation to Eskom what welding processes shall be

used. Prior to the awarding of the contract, an agreement must be reached between the Contractor and

the Eskom IWE with regards to the acceptable welding processes to be used during the burner

manufacturing process.

3.5.2 Welder approval

All welder qualification records shall be approved to the latest requirements of the relevant EN codes,

and the Standard for Welding Requirements on Eskom Plant. The welder certificates shall be presented

to Eskom’s IWE for acceptance prior to the commencement of work.

The welder qualifications for overlay welding, including automated and semi-automated processes shall

be submitted to Eskom’s IWE for acceptance prior to the commencement of work.

3.5.3 Repairs

All repairs to components and the relevant testing thereof shall be agreed with the client before the commencement of work. The applicable documentation shall be put in place. The approved documentation shall be included in the data book.

The repair procedure for welds and weld overlay hard-facing shall be submitted to Eskom for acceptance prior to the commencement of work.





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The minimum size of inserts into cones and cylinders shall be 200mm.

3.5.4 Weld gap

It is required of the Manufacturing Contractor to comply with the weld preparation dimensions as

indicated in the welding procedure specifications (WPS). Root gaps in excess of the WPS will be

considered when:

i. Welding gaps outside of this definition can only be built-up with the agreement of the

Eskom IWE.

Eskom is under no obligation to accept such a deviation.

3.5.5 Hard-facing

The application of overlay welding to protect components against erosion is common in pulverised fuel

burners. The latest requirements of the EN Codes shall be used to qualify overlay welding procedures. It

is acknowledged that certain overlay welding does crack, and has a propensity to form pores. The

acceptance criteria for cracks and porosity shall be as follows:

Table 18: Cracking of hard-facing

Table 19: Single and Cluster Porosity

Single and cluster porosity (Chrome carbide overlay material)

A cluster of pores with individual pore diameters

less than 2.5 mm, and less than or equal to five

pores located within a circle with a diameter of less

than 20 mm.

Acceptable

A cluster of pores with individual pore diameters

between 1 mm and 2.5 mm, and more than five

pores located within a circle with a diameter of less

than 20 mm.

Not acceptable – To be repaired

A single pore with a diameter greater than 2.5 mm,

regardless of the location.


Note: A pore is defined as a void with a diameter greater than 0.5 mm

Cracking of hard-facing (Chrome carbide overlay material)

Any crack with a width of less than or equal to 1

mm, regardless of length and direction.

Acceptable

Any crack with a width greater than 1 mm and less

than or equal to 2 mm with a length of less than 30

mm.

Acceptable

Any crack with a width greater than 2 mm and a

length greater than 2.5 mm.






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Table 20: Linear Porosity

Linear porosity (Chrome carbide overlay capping welds)

Linear porosity with individual pore diameters less

than 2.5 mm, and less than or equal to five pores

located within a 30 mm length of capping weld

material, regardless of weld width.

Acceptable

Linear porosity with individual pore diameters

between 1 mm and 2.5 mm, and more than five

pores located within a 30 mm length of capping

weld material, regardless of weld width.


A single pore with a diameter greater than 2.5 mm,

regardless of the location.


Note: A pore is defined as a void with a diameter greater than 0.5 mm

3.5.6 Separation of materials

Stainless steel and carbon steel consumables shall be stored separately in the consumable store room.

The Manufacturing contractor shall separate stainless steel from carbon steel in the workshop, in order

to prevent the contamination of materials. The areas for stainless steel and carbon steel shall be clearly

identified in the workshop.

3.5.7 Surface finishes

Welding slag and spatter shall be removed from all completed welds and the adjacent base metal. The

method of cleaning shall be by means of brushing and grinding. The Contractor shall take the required

preventative measures to minimise the amount of spatter.

Hammer marks are not permissible on the components. Flange sealing faces shall be free from any

mechanical damage and surface irregularities.

3.5.8 Non-destructive testing

Welded connections shall be non-destructively inspected. The extent of NDT and the acceptance criteria

levels to BS EN ISO 5817 pertaining to weld imperfections shall be agreed upon between the Contractor,

the EDWL and the Eskom IWE prior to the award of the contract. A reduction or increase in the

inspection rate is purely at the sole discretion of Eskom.

The Eskom rules and requirements for NDT will be as stated in the latest revision of the following:

• 240-83540088 - Requirements for NDT on Eskom Plant Standard.

• 240-83539994 – Eskom NDT Personnel Approval (NPA) for quality related special processes on Eskom Plant Standard.

Stainless Steel shall be, and shall remain 100% surface crack tested throughout the duration of the

contract.





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3.6 QUALITY CONTROL

3.6.1 Inspection and test plans

Inspection and test plans shall be developed that clearly stipulate the work to be performed in a logical

order. This shall include all hold, witness, review and surveillance points required for inspection and

verification. The inspection and test plans shall be submitted as part of the Contractors documentation

prior to the commencement of work.

No work may commence until the ITP’s are accepted by Eskom.

3.6.2 Fit for purpose

Engineering codes have a “Non-conformity” clause stating that “Unless otherwise stated, work-pieces

exceeding the general tolerance shall not lead to automatic rejection provided that the ability of the work-

piece to function is not impaired”. Eskom is under no obligation to approve a non-conformity. Under this

Standard, rejection of work-pieces exceeding the general tolerances is automatic.

3.6.3 Material certification

Prior to material acceptance, an inspection shall be carried out. Each consignment shall be examined as

appropriate for:

Compliance with the purchaser’s specifications,

Physical damage,

Adequate storage protection,

Conformance to dimensional and material property specifications,

Proper identification and marking,

Compliant documentation, such as material certification (mechanical testing and chemical

composition).

Materials found deficient during this inspection shall be identified and segregated from acceptable

materials, and moved to a quarantine area. Rejected materials shall be returned to the vendor.

3.6.4 Material handling

Handling of materials shall be controlled to prevent damage and contamination with peripheral harmful

matter or substances such as oil, grease or dirt. Platework shall be carefully handled during receipt,

storage and installation to prevent any scratching, gouging and nicking that may affect the integrity of the

burner.

Platework should not be dragged across hard surfaces, sharp edges of steelwork, concrete and gravel.

3.6.5 Storage

Platework and manufactured components shall be stored in a dry space and protected from

contamination and physical damage. Containers or stacks shall be clearly marked with their contents,

material designation and if applicable, plant identification code. All burner components shall be packaged

in such a manner that they can be stored externally without causing corrosion to the component.





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The storage and handling of stainless steel plates and / or components shall be compliant with the

requirements as specified in the latest revision of BS EN 1011-3.

3.6.6 Documentation packages

Documentation to be compiled and retained shall comply with the relevant statutory and safety

stipulations. The minimum index requirement for the data books that shall be supplied to Eskom is as

follows:

Index

Instruction for work

Inspection and test plans

Weld map

Weld matrix

Approved Manufacturing drawings

As-built drawings

Non-destructive testing procedures

Non-destructive testing reports

Non-conformance reports

Concessions

Repair procedures

Material certificates

Consumable certificates

Welding procedures

Welder qualifications

Certificate of manufacture

Release notes

Inspection reports

Calibration certificates

Eskom approval and qualification for NDT company and their Technicians

Approved additional procedures

Sub-contractors data books, including component data sheets

3.7 DRAWINGS

All drawings prepared by the Contractor relevant to the contract shall comply with the requirements of

the latest Eskom Engineering Drawing Standard, as listed in the normative references of this document.

The drawings shall become the property of Eskom, and shall have an Eskom logo. Drawings shall be

transferred to Eskom in electronic format, in a programme compatible with Eskom’s drawing office

requirements.

All drawings used in the workshop shall have an “Approved for manufacture” stamp. It shall be the latest

revision, and it shall be accepted by Eskom prior to the commencement of work.





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3.7.1 Manufacturing drawings

It is the Contractors responsibility to prepare manufacturing drawings. These drawings shall indicate all

dimensions and code acceptance standards, as well as this Standard number.

3.7.2 Tolerances on drawings

Tolerances for flatness, ovality, linear dimensions and circularity shall be indicated on the drawing in

table format should they deviate from the accepted tolerances in this Standard. Any deviation to the

agreed tolerances in this Standard shall be presented to the Eskom EDWL for consideration. Eskom is

under no obligation to accept any deviation to this Standard.

3.7.3 Critical dimensions

All manufacturing drawings will indicate what dimensions shall always be inspected by Eskom staff. To

avoid confusion, all critical dimensions shall have a rectangular box around the dimension. An example

of such a critical dimension is as follows:

2 543 mm

Eskom staff and the Manufacturing contractor shall agree before the finalisation of the drawings what

dimensions are deemed to be critical. Eskom reserves the right to inspect all dimensions as indicated on

the drawing, including non-critical dimensions.

3.8 SUPPLIER ASSESSMENTS

Eskom reserves the right to audit / assess a company’s workshop where manufacturing takes place. The

assessment shall include a technical team, including the Eskom IWE to assess the companies welding

capabilities before a contract shall be awarded.

3.9 GENERAL ASSEMBLY

3.9.1 Bolting

The grade of bolt, as well as the torque value shall be indicated on the manufacturing drawing. All bolts

shall be torqued to the correct tightness, prior to delivery to site. The torque value shall be agreed upon

between Eskom staff and the Manufacturing contractor prior to the finalisation of the manufacturing

drawings. Washers shall always be used on both sides of the bolt, unless the bolt is welded to the

burner. In such a case, only one washer is required on the “nut” side of the bolt.

All bolts, when tightened to the correct torque value shall have a minimum of two threads protruding from

the nut, with a maximum of 6 threads.

3.9.2 Passivation and pickling

The Contractors post-weld pickle and passivation procedures shall be submitted to Eskom for

acceptance.





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3.9.3 Painting

No component may be painted until it has been released by Eskom’s quality control officers, and/or the

appointed Eskom Supervisor for the project. All components shall be painted, prior to delivery to site.

The surface preparation shall comply with the paint manufacturer’s requirements prior to painting. A

minimum of two coats of paint shall be applied to all surfaces. Only water based paint shall be used.

The Contractor shall submit to Eskom their corrosion protection procedure for bolts, prior to the

commencement of work.

3.9.4 Jigs

It is advised to manufacture all components within manufacturing jigs and fixtures to ensure conformity,

uniformity and reduce the degree of distortion due to welding. All manufacturing jigs, fixtures and

drawings shall become the property of Eskom on completion of the contract.

All manufacturing jigs and fixtures are to be manufactured according to manufacturing drawings. These

drawings shall be submitted to Eskom for review and acceptance.

3.9.5 Transportation frames

The usage of transportation frames to safely transport and store the components on site shall be

designed and approved by a person registered with the Engineering Council of South Africa. The

transportation frames and drawings shall become the property of Eskom on completion of the contract.

All transportation frames are to be manufactured according to a manufacturing drawing. These drawings

shall be submitted to Eskom for review and acceptance.

3.10 MATERIAL CERTIFICATION

3.10.1 Material of construction

All materials used in the manufacture of the burner shall be certified by the manufacturer. The

manufacturer shall have a quality assurance programme for material control and verification. The

certificate shall include the mechanical and chemical tests performed.

The quality management system shall comply with ISO 9001-Quality Management Systems

requirements.

3.10.2 Certificates of compliance

All materials used for the manufacture of the Low NOx Burners shall have an EN ISO 10204 3.2

certification. In the exceptional cases where a 3.2 certificate is not available, the Contractor may request

a concession from Eskom to use a material with a 3.1 verified certificate. Eskom reserves the right to

reject such a concession.

In these exceptional cases, a verified 3.1 inspection certification will be accepted, provided that the

following is agreed and adhered to:

There is agreement between Eskom and the Contractor that the case in question is deemed to be an

exception to the rule. Leniency may be given to plant items classified as Level 2 and 3.





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Available results from all tests will be evaluated by experienced engineers, and if need be with the

inclusion of Eskom’s Materials Division.

Destructive tests are carried out on random samples to prove the material’s mechanical properties,

provided that all the components are from the same batch of material.

Destructive testing might include any or all of the following:

Tensile testing at room temperature and operating temperature (transverse).

Impact testing at room and operating temperature (longitudinal sample with transverse notch).

Metallography for microstructure and inclusion assessment and hardness testing of a sample in the

laboratory.

Full chemical analysis on material samples (not filings). Material filings shall be taken on random

samples to prove the material properties, provided that the components being tested are all from the

same batch of material. Samples for full chemical analysis are preferred, but portable spark emission

spectrometry techniques can be used to check all samples if needed.

All material, whether it is a Carbon steel, Chrome Molybdenum or Stainless Steel shall be tested. Testing

is not required on secondary components such as bolts and nuts.

3.10.3 Material identification

Material platework shall be marked with the alloy, thickness, code of manufacture and other information

required. The marking method applied shall not affect the integrity of the material. “Easi-peel” stickers

are not acceptable. The preference is low stress hard stamping. The Contractor shall submit their

material identification procedure for acceptance prior to the cutting of material.

3.10.4 Inspection and test plans

Inspection and test plans shall be in place, agreed to and signed by all parties before work may

commence. It is required to have an inspection and test plan per manufactured item in order for Eskom

to release the items for use on the plant. The critical dimensions on the drawings that accompany the

inspection and test plans shall be signed by the relevant parties, prior to the release of the component.

On completion of a batch of burners (normally per Unit), the Manufacturing Contractor shall consolidate

the inspection and test plans with all other supporting documents and send it to Eskom’s document

management department for filing. This shall be done in electronic and hard copy format.

Eskom undertake to have adequate Supervisory staff allocated to the project.





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4. AUTHORISATION

This document has been seen and accepted by:

Name & Surname Designation

Anton Hart Middle Manager, Boiler Auxiliary

Yokesh Singh General Manager

Morris Maroga Middle Manager, Boiler

Sandile Peta LDE, Tutuka Power Station

Christo van der Merwe LDE, Majuba Power Station

Avinash Maharaj LDE, Matla Power Station

Hamresin Archary LDE, Kriel Power Station

Morris Sher Supervisor, Camden Power Station

Dave Sher Supervisor, Camden Power Station

Marcel Rabie IWE, Camden Power Station

Chris du Toit Site Engineer, Camden Power Station

Jacques van Rensburg Site Engineer, Grootvlei Power Station

Dr Robert Clark Chief Engineer

5. REVISIONS

Date Rev. Compiler Remarks

December 2015 0.1 Dr RM Clark First Draft for Internal Review

February 2016 0.2 Dr RM Clark Final Draft for Comments Review Process

June 2016 0.3 Dr RM Clark All comments included in report after Review Process

September 2016 0.4 Dr RM Clark Updates Completed Final Draft after Review Process

September 2016 1 Dr RM Clark Final Document for Authorisation and Publication

6. DEVELOPMENT TEAM

The following people were involved in the development of this document:

Dr RM Clark

S Peta

C van der Merwe

H Archary

A Maharaj

C du Toit

J Janse van Rensburg

M Sher

D Sher

M Rabie





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7. ACKNOWLEDGEMENTS

All members of the Low NOx burner team

The valuable inputs from the Boiler Supervisors at Camden Power Station

The valuable inputs from the Pressure Part CoE (IWE involvement)

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